title: Acute kidney injury in patients infected by H1N1: clinical histological correlation in a series of cases.
abstract: BACKGROUND
  Influenza A (H1N1) virus was first reported on April 2009 and, since then, several studies have reported the characteristics concerning the clinical presentation and pulmonary involvement. However, accurate information about the acute kidney injury (AKI) and kidney histopathological findings in these patients remain scarce.
  
  
  OBJECTIVE
  To describe the kidney histopathological findings of 6 patients with H1N1 who developed AKI and underwent kidney biopsy, correlating them with clinical features.
  
  
  METHODS
  We studied six patients admitted to Hospital de Clínicas UFPR with a PCR-confirmed diagnosis of H1N1who developed ARF and underwent kidney biopsy. We reviewed their medical file and the microscopy findings of the biopsy.
  
  
  RESULTS
  Clinical and/or laboratory evidence of AKI was present in all cases, and only one did not present oliguria. Kidney tissues revealed glomerular lesions in two patients: one patient, with systemic lupus erythematosus, showed changes consistent with lupus nephritis class III A-C according to the ISN/RPS 2003 and focal thrombotic microangiopathy; the other one had intercapillary nodular glomerulosclerosis, but without clinical or laboratory evidence of diabetes. Vacuolar degenerative tubular changes were present in all cases, with focus of oxalosis in two cases. Mild to moderate atherosclerosis was found in two patients.
  
  
  CONCLUSIONS
  In this study, varying degrees of vacuolar degenerative tubular changes were present in all patients, but there were no signs of acute tubular necrosis. It seems that in the present study a prerenal cause of acute renal failure was the main involved mechanim to explain the cause of renal failure in these patients.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Sevignani
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Soares
authors.forename: Gustavo Lenci
authors.initials: GL
authors.lastname: Marques
authors.forename: Ana Karyn Ehrenfried de
authors.initials: AK
authors.lastname: Freitas
authors.forename: Arthur
authors.initials: A
authors.lastname: Gentili
authors.forename: Domingos Candiota
authors.initials: DC
authors.lastname: Chula
authors.forename: Marcelo Mazza do
authors.initials: MM
authors.lastname: Nascimento
mesh_terms: D058186:Acute Kidney Injury / Q000473:pathology* / Q000821:virology*; D000328:Adult; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000150:complications*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D055815:Young Adult